US2602647A

US2602647A - Tubular contactor with conical distribution plate

Info

Publication number: US2602647A
Application number: US218479A
Authority: US
Inventors: Roy W Miller
Original assignee: Standard Oil Co
Current assignee: Standard Oil Co
Priority date: 1951-03-30
Filing date: 1951-03-30
Publication date: 1952-07-08
Anticipated expiration: 1969-07-08

Description

R. w. MILLER 2,602,647-

TUBULAR CONTACTOR WITH CONICAL DISTRIBUTION PLATE July 8, 1952 Filed March 50, 1951 INVENTOR. Roy W Miller MQQM .qrrozemsv sien" f ct rvanes: approximate;

Patented July 8, 1952 TUBULAR CONTACTOR WITH CONIGAE DISTRIBUTION PLATE Roy: W. Miller; Hammond,, Ind, assignor to Standard: Oil, Company, Chicago, 111., a coma-- ration ofzlndianae Application March-36, 1951;Scrial'No; 2185479 110mm. (oust/@22 4) This inventioni relates toimethod" and: means for providing conta'cti between gasiform fluids; and finely divided solid materials. Mora..partic.= ularly the: invention: relateszto l'distributing; a heterogeneous. dense turbulentz suspended; mix-- are of? gasiform'; fluid i: and: finely divided solids;

througlia bundle of t'ubesi:

Itihas: long been: recognized: that; a. mass: of finelydivided solidi materials; can: be carried; up;- wardly by a: gas toi provide a-zvfluidized bed: of; finely divided solid -materials=:andw tot provide: ini-- tiinate'contact ofithergasesandzthe;finelydivided solids? It:v has I also: been proposed: that such: a fluidized mass be. divided: into a; plurality: of" columnarbodies forthe'purpose of. indirect heat exchange; However; itihas' been observed. that im supplying aiheteifogeneous: suspended; mixture of finelydividedi solids? and carrier gas. from" a; single conduit to: a plurality: of; parallel tubular conduitst there is unequal; distribution: of; the finely: divided; solids: and: gasesi.through. the: bundleof tubes: L

The solidsin thisi heterogeneous mixture; exe hibie-their own: special flOW-J characteristicslwhile. thefl'ui'd component behaves iin azwholly diiferent manner; For example. when: a; flowing: solid emerges from a" pipe? section: of: small diameter to a conduit concentrically: of larger-diameter; suchas 1 a -bu'ndlez of tubes. the solids obey; the

laws of motionz and ten-(ii toai continue: in: their normal path as restricted. the smaller pipe; 'I lie fluid; being lessrdensm than; the; suspended solids;- reaches the peripheral area: of the larger conduit in prefe'renceito' thez'solim'particlesL This phase separation, although'hot-i sharp; gives a var-ialzile solids'eto-fiuid; distribution: across; the larger conduit; or bu'r'idle, 'withi morezsolidsziflow ing through the center tubes andtthe-zmajority of the fluid through the outer or peripheral tubes. The solids flowing through the center tubes, being the denser materiaL-causes a greater static pressure drop than the fluid at the.outer tubes. Therefore the. fluid in the outervtubes must make .upin velocityipressurje drop the diff ierencedh statie head. caused I the mqredense solids" in the 'centraft'ub'es, which "means a greatervelopity for the fluid .in the outer tubes of the cooler than in those near the center; This flow maldistribution causesmany. complications. It greatly increases theero'sion' bfthe outer tubes of the coolerr. due -te the 'factith'at' the cro thekcube of the velecity and the jflrst new the density; -Eikewise, the tiibe s'heet i's *subjec te severe ero sionf- Furthermore} the --1ineven flewthrough the heats exchanger bundle causes variance in heat, transfer; through the tubes. sincethe vejlocity, the heatcapacity, and the. exit: tempera-- tures will vary from tube to tube. L

It istherefore; anobject: of this invention to provide a: method: and means. for, introducing; heterogeneous mixtures ofgasiform: fluids and solids: uniformly across the entire flow'area ofa contacting= chamber. vention'is to'providemethodi and; means for sup-=- plying: such heterogeneous mixtures? to. a bundle. of parallel tubes'witha minimum erosion-of; the tubes: located on: the: periphery? of the bundle: A furtherrobject-giscto provide a: contacting: cha-m" her which permits eifective and controlled con tact of'finel'y, divided; solids and gasiform fluids with? aminimum pressure; dropj caused by the uneven: flow of finely divided: solids through, the tubes.- An additional object-is: toyprovidean ap-- paratuslwhich: permits higher; heat-,transfer-ratesbetweencooling; fluids: and heterogeneous mix-- tures of solids and'carrier gasesrby; maintaining uniform flow and temperature: gradients across thementaatingchamber; 1

mm'ore specific: objectof the invention is toprovide" an, improved; contacting? chamber for controlling; the temperature of: a. heterogeneous mixture; of finely divided; solids; and ga'siform' fluids; and; for; maintaining effective: heat transfer -from such "afluidizedmixture. Other objects. will become apparent as the detailedi description of my;-inventionproceeds: i

I It has. heretofore: been; proposed: to: minimize the defects: outlined above by employing a grid or perforated plate for supportingilthe finely divided solids and for introducing: the gasiform fluid at uniformly" spaced. points acrosstheflow area of the: contactingvessel: l Nevertheless contactors for fluidized masses of finely, divided solidsiofiv this. generaktype: have; suffered from a number of? major difficulties; Int addition-towinlet and grid fouling, erosion of the grid: orifices; Ofi'thG; tube; bundle and of; the tube sheetjhas been'severe.

These difficulties are especiallygpronouncedz in a-rxzcatalys'tz cooler ofxa:v fluid catalytic; cracking unit-c Such: aacatalysti cooler isausedifor thepurr pose" of: cooling the catalyst and reeyclingeit; to the; regeneraton for ftemperature control therein; In mostiinstances theicatalyst;re: gzfinelyidivided clay; silica; aluminarand" the like; and: airiflow through a pipe of. snfall3 diameter; and: emerge into t'ubesw'f ;a; cooling; sectiomhundle; in a: larger diameter pipe; The: large ipe driest-not; 'necesisarily' have: a%- larger netrfiowr area than 1the;small Another object of the intpipe, since a tube sheet extends across the bundle diameter with tubes in which the catalyst and air flow for heat exchange purposes with a liquid in the tank surrounding the tubes.

The catalyst being more dense than the air continues in its normal path through the central group of tubes in the cooler andthe air being more easily displaced laterally travels preferentially to the outer or peripheral tubes. This phase separation is not sharp but ample to give a variable catalyst-to-air distribution throughout a the catalyst cooler with more catalyst fiowing' through the central tubes and the bulk of the air through the outer tubes. through the center tubes causes a greater static pressure drop than the air through the outer tubes. Consequently, there is a bypassing by the air at a high velocity with a dilute suspension or heterogeneous mixture of catalyst through the peripheral tubes. This uneven flow distribution causes excessive erosion on the tubes located at the periphery of the cooler; increases pressure drop through the tubes; and reduces the heat transfer rate. I

Briefly, I attain the objects of my invention and elirninate'the described difiiculties byproviding a tapered or inverted conical bafile contain-;

ing a plurality of ports, the areas of which are proportional to the tube area above at any radial distance. The inverted conical bafiie is placed at through the conical sheet is equal to or greater than the total cooler/tube area.

The catalyst which strikes the solid portion of the conical sheet is directed outward and upward until it finds an opening'through which it may flow, the area of this opening being proportional to the number of tubes located above. With this type of bafile control, the heterogeneous mixtureof catalyst and air is uniformly.--'distri-' buted across and within the individual tubes of thecatalystcooler.

The details of construction and configuration of the apparatus will be apparent fromthe fol-.

lowing description 'takenwith the accompanying drawings wherein: 1 r Figure 1 is anelevation of a contactor employing my conical dispersing bafile;

Figure '2 is a partial section'of the" apparatus of Figure 1; 1

Figures 3 Sand 4 are'top and side views; respectively, ofone embodiment of the conical bafiiepan'd I J A Figures Band 6 are top and side views, respectively, of another embodiment ofthe conical dispersing baffle: 1

Referring to the drawing, my apparatus comprises an inlet line I0. merging with a tapered section :I lwhich is flared upward and outward to the full diameter ofthecontactor .I2. The main body for the contactor or cooler 12 is formed of a bundle 'of tubes l3between alower tube sheet l4 and'upper tube sheetslfi in a shell vll.,;,-'lihese tubesl [:3 may belfrom about 1.0 inch to3.0;inches in diameter. and they arei'surroundedbyalcooling liquid such as water which may be introduced The catalyst flowing into shell I! through line It. The heat extracted from the heterogeneous mixture of gases and solids flowing in tubes 13 converts the water to steam which is withdrawn through line IS. The stream of gases and solids from the individual tubes l3 are commingled within tapered reducing section I9 and withdrawn bytransfer conduit 20. I

The dispersing plate 21 is provided with a plurality of ports 22, the aggregate area thereof at any radial distance from the center being proportional to the total number of tubes l3 thereabove. The angle of the cone or dispersing plate 2| should be such as to approximately bisect the'angleformed by the tube sheet M and the sloping wall of the reducing section II between the inlet pipe and the cooler shell H. The angle formed by the conical distributing plate 2| will vary between about 15 and degrees measured from the tube sheet Hi, the preferred angle being. that which bisects, the angle .formed by'the tubejsheet l4 and the wall of the reducing section I l. 7

' An important advantage of this typeoi distributionplatell is to attain uniform distribution of the solids as well as of the carrier gas, The conical shape of the plate 2! provides an outer deflecting surface .for the flowing solid 0 as shown in Figure 2, and the distribution of the ports .22;

causes'the bulk of the flowing solid to move. to the outer edge of the plate 2|.

The distribution and spacingcf the slots or ports 22 in the distribution plate 2| are critical. The area of the ports 22 at any radial distance from the center isxproportional to the flow area of'the tubes .13 downstream.- -When the tubes. I3 in the bundle are evenly spaced and symmetrically arranged, the proportional areaof the ports 22 will vary directly as the distance from the center of the plate 2|. In addition, the ports 22 are spaced about the surface of the conical dis: tributing plate 2| so as to deflect the desired proportion of the flowing solids toward the outer edge 21a of the plate all." The annular-surface of the plate is provided with ports 22 having a a total area ofirom 1.0 to 3.0.times the flow area of the tubes 13 in the bundle. In the preferred arrangement, the area of the ports 22 is equal to the total flow area of the tubes 13 in the bundle. Thetubes 13 are arranged in symmetrical con-1 centric 5 groups within .the contactor I 2.

'rhe total area of the ports-22 at a given level within the conical dispersing platep2l is proportional and"v preferably equal to the total areaof the tubes. |3-in the bundle..- The'port area vin'the conical ,plate 2| at any height Hx-measure'dyfrom the base of the cone can-bev defined by the expression.

. i e v V I T total tube area irisq. in; I li r heightfiof annulai' Section 21b of cone R radius of basebfconical'dispersing platei 'and nen' .j i J 9;:angle between tubesheet 14' and conical plate Qtport area/tube area i V A typical contactor oft he type described the drawin ;,c.o r s a .vert cel. ham r, H. p which may be abo teet in a r n! about. 3.? feet :in height,- jThe inletjconduit l 0,-.-may;.;be about. 4. feet 4 lnchesiln-r diameter and the outlet gang-e or-* transfer {line 20 i's of correspondiiig 'size; 'I'h'e iridi-vidua tubes-I 3 withmi the= shell I12 may; be about 755' eet m length -andf. about 1%: inchesrin" diameteri: About -580= of these"- tubes. may "be symmetrically arranged between tube-sheets; I4 and-:.I5-on1a.square.pattern. The dispersing plate 2| has a diameter or base corresponding to the inside diameter." of; theishell II: and may be mountedat the top of the reducing section I I as shown in'Figure' 2'. Thetapered section I Iimay be about 8 feet long and is preferably "lined'with' a protectivma'ter-ial 23 such1asn fiiinnite.

It wilkbe seen in Figures Sand 4 and Figures;5 andrfi thatthe area of the ports-.-22 isisubstantially greater toward the, periphery of. thQxdiS- persing-plate 2|. The gasesg. pass through.the

ports 22 substantially normaljtothe conicallplane surface of the plate 2I whereas the catalyst c has a tendency to-travel outwardly-- and upwardly alonggthe surface of the: dispersing plate; 2'I- unitil-.it reaches a port. 22 after: which the: particle tends to travel vertically upward into a tube I3.

In Figures 5 and 6, I have illustrated a drilled type plate 2 I. The ports 22 are shown as varying in size but it is contemplated that the holes can be of the same diameter but spaced to obtain the correct open area for any radial distance from the apex of the conical plate 2|. The diameter of the ports 22 may be 0.5 to 2 or 3 times the diameter of the tubes I3. In the illustrated apparatus, the inlet pipe III has a flow area about equal to the flow area of the tubes I3 in the bundle within shell I'I. Therefore, the area of the drilled ports 22 in the subcone 2| a having a base area equivalent to the inlet pipe I is only one-fourth the area of the inlet pipe I 0. The remaining 75% of the drilled area is in the annulus or peripheral edge 2Ib of the distribution plate 2|. It should be noted that in the area of the conical plate 2| covered by the smaller inlet pipe I II, 75% of the solid surface is used to deflect the flowing solid 0 to the ports 22 in the outer edge 2 lb and only one-fourth of the flowing solid will therefore enter the ports in the central area :2'Ia. In this manner, 75% of the solids flowing to the central conical section 2 Ia will be deflected ing in a direction parallel to the tubes and per- 0 pendicular to the tube sheet I4, erosion of the tubes I3 and of the tube sheet I4 is, minimized. It has been established that erosion of the plate and tube is greatest when impingement is at an angle substantially less than 90 degrees and more than to 10 degrees. Thus, by directing the heterogeneous stream substantially perpendicularly to the tube sheet I4 and in alignment with the longitudinal axis of the cooling tubes I3, erosion is reduced to a minimum.

Likewise, by distributing the stream to the peripheral tubes I3, a balanced condition is maintained throughout all of the tubes regardless of their position within the bundle. This balanced operation likewise reduces erosion by reducing the velocity of the flow through any tube or group of tubes.

In general, a velocity below about feet per second will not permit a stable fluid flow through the cooler tubes I3. Conversely velocity flow above about feet per second causes excessive erosion. By the use of my catalyst dispersing plate 2|, however, stable fluid flow can be obtained at the lower end of this range of between about 20 and 35 feet per second, thereby obtainingi optimumi heat'i transfer: .ratesz; reducing. eras sion'at'o. .aaminin'mmaand. substantiallyeliminating, the-bypassing; of any: tube: orxgroup of tubes: due: to :unequali distributionzofii'solids rand; gasesiacross; theibundleiofitubes..v. s 2: 2 Although: I: haves described myr-ainventiomirrterms; ofi specific? examples: are; set: forth in considerable: detail;,. it; shouldi berunderstood that-j'tnesmarmby wayiof zillustration only: andJtha-t' theainventiorriise not limited: theretoi. since: alrternative'iembodiments.andi-operatingztechniques. willliibecomer apparent-ate; those: slcflleddnthet art-- inzvi'evurof mysdisclosure: Accordin lia-modifica tions of my invention.arezcontemplafifihwithout; depaittingrfronnthes spirlttof' the; describediinvention: orrfi'om .th'ezscopeQoflthmappended claimai -Jfcltaai'irrz;. q l,.-.,Anzapparatus ,adaptedto effect.- heat. ex:-, change between: a1.heterQgeneousstreamr gasi form; fluid; and finely; divided.- solidss which co ne prises; an generallm cylindrical; shell, a bundle; oiparallel tubes arranged between upper and lower tube sheets within said shell, a reducing section at each end of said shell, an inlet conduit and an outlet conduit communicating with the respective reducing sections, the improvement which comprises a conical distribution plate having a ported central conical section and a ported outer annular conical section, the ports in said central conical section and said annular conical section being circumferentially offset so as to provide a substantial deflecting surface on said central section extending to the ports in the annular section.

2. The apparatus of claim 1 wherein the area of the ports in the distributing plate is proportional to the area of the tubes immediately above the plate.

3. The apparatus of claim 1 wherein the conical distribution plate is disposed at an angle of between about 15 and 45 degrees with respect to. the lower tube sheet.

4. The apparatus of claim 1 wherein the conical distribution plate bisects the angle between the tube sheet and the wall of the reducing section adjacent the inlet to said shell.

5. The apparatus of claim 1 wherein the ports comprise a plurality of tapered slots.

6. The apparatus of claim 1 wherein the ports comprise a plurality of substantially circular openings arranged in symmetrical radial groups.

7. The apparatus of claim 1 wherein the surface of the central conical section comprises about 55 to percent imperforate area and about 45 to 25 percent port area, and wherein the annular section comprises about 55 to '75 percent port area and about 45 to 25 percent imperforate area.

8. In an apparatus for flowing a heterogeneous stream of gasiform fluids and finely divided solids through a bundle of parallel tubes, the improvement which comprises a ported conical distributing plate having its apex directed upstream, said conical plate having a central portion wherein the solid area predominates over the port area and an annular portion wherein the port area predominates. over the imperforate area.

9. The apparatus of claim 8 wherein the proportion of port area to imperforate area in the central portion and in the annular portion is directly proportional to the number of tubes above the distributing plate within the respective central portion and annular portion.

10. The apparatus which includes a bundle of parallel tubes arranged between tube sheets within" a shell adapted to circulate a heat transfer medium about 'said tubes, the improvement which comprises a conical distributoryplate arranged belowthe bundleof tubes,said-plate comprising a central conical portion and. a merging. annular truncated conical portion'having a slope at an angle of between about15 and 45 degrees with respecttothe adjacent tubesheet, a plurality of ports in said plate; the area'of said ports progressively increasing from the apex to the base of the said conical plate, and substantially imperforate portions of said'central portion deflectingsolids upwardly and outwardly to the ports in the said annular portion. v V

- 11'. The method of heat tra'nsferrfrom a heterogeneous stream of finely divided solids suspended in a gasiform fiuid which comprises the steps of passing said stream upwardly through a heat exchange zone including a bundle oiheat exchangetubes, and preventing a phase'separa tion between said solids and 'gasiform fluid prior to introduction of said stream to said bundle by deflecting about '75 percent of the solids upwardly andv outwardlyto ;a peripheral'portion and passing about 25 percent of the solids through a central portion of therheat exchange zone. V

ROY W. MILLER.

REFERENCES CITED Thefollowing references areof record in the me ofthis patenty NITED STATES PATENTS.

France Oct. 13, 1921